The invention also relates to an arrangement for carrying out the methods.
In order to provide a quantitative measurement of the velocity of the blood in the arteries a method for the ultrasonic imaging of velocities is based essentially on knowing the angle between the incident ultrasonic beam and the local axis of the vessel. The resulting information can be displayed, for example, by color encoding. This holds for all ultrasonic signal processing methods currently used to produce a color-encoded representation of the flows in any commercially available echography apparatus. Moreover, reliable determination of this so-called Doppler angle is necessary in order to enable extraction of echographic data of parameters whose measurement is rather complex, thus making further progress in the study of, for example arterial behavior.
Therefore, it would be important to realize a method for extracting the value of the Doppler angle from a medical ultrasonic image that can be carried out automatically with a high precision, for example within about 1 degree.
The Doppler angle still is a difficult topic in all commercially available apparatus: the operator must determine the value thereof in a rather approximate manner by judging the alignment of a small line segment he traces in the image with respect to the axis of the blood vessel studied.